1. Field of the Invention
The present invention relates to a pressurized fluid hose for conducting pressurized fluid discharged from a pump to a fluid operating device as a power steering apparatus and the like.
2. Discussion of the Prior Art
In power steering apparatus for use in automobiles, pressurized fluid discharged from a pump has a pulsation, whereby a noise occurs in the power steering apparatus. To reduce the pulsation of the pressurized fluid, a spiral tube formed by spirally winding two band members is disposed in a flexible rubber hose located between the pump and the power steering apparatus. The spiral tube makes in the rubber hose two pressurized fluids which are different in phase of pulsation and causes the two fluids to interfere with each other thereby to reduce the pulsation. In manufacturing, the spiral tube is inserted into a steel pipe which is secured at its one end to the rubber hose and is secured to the steel pipe by being caulked with a caulking tool from the outer surface of the steel pipe.
FIG. 4 shows a caulked portion at which a spiral tube 20 and a steel pipe 13 are fixed in the prior art. The steel pipe 13 is pressed and deformed by a caulking tool 30 having a pressing surface parallel to the steel pipe 13, at its thin one end 131 of a constant thickness shown by the broken line, whereby the spiral tube 20 is fixed to the steel pipe 13.
The pressing at the caulked portion causes the thin one end 131 to be deformed as indicated by the solid line, so that an inside diameter of the thin one end 131 is abruptly changed. As a result, a large clearance is formed between two outer and inner band members of the spiral tube 20 located in the vicinity of the thin one end 131. It has been known that the change in fluid leakage which takes place through the large clearance adversely affects the operation to reduce the pulsation in the pressurized fluid, and the operation to reduce the pulsation is disadvantageously weakened by the influence of the large clearance.
Further, it is difficult to set to a predetermined relation the relative position between the band members of the spiral tube 20 and the extreme end of the thin one end portion 131. To be more exact, the extreme end of the thin one end portion 131 may be in the same axial phase as the outer band member of the spiral tube 20 or as the inner band member thereof. Such dispersion of the relative position between the band members and the extreme end of the thin one end portion 131 occurs on individual hoses, so that the width of the clearance formed between the band members varies on each hose. The variation of the clearance results in the dispersion of fluid leakage, and hoses which are not effective in the operation to reduce pulsation may be produced.
To solve the aforementioned drawbacks, as disclosed in Japanese Examined utility Model Publication No. 2-6315, a pressurized fluid supply hose of the construction is known that a sealant is coated on the outer surface of one end portion of a spiral tube and that the spiral tube is fixedly inserted into a steel pipe through the sealant. Further, as disclosed in Japanese Unexamined Utility Model Publication No. 1-144595, another pressurized fluid supply hose of the construction is known that a cylindrical sealing member is inserted into one end of a spiral tube and that the spiral tube is inserted into a steel pipe and is fixed by caulking at the portion of the sealing member. These hoses are able to prevent the clearance between band members of the spiral tube from being made large by caulking from the outside of the steel pipe and thereby to avoid the variation in the operation to reduce pulsation among the hoses. However, the known hoses necessitate a process for coating the outer surface of the spiral tube with the sealant, or producing the sealing member and then inserting the sealing member into the spiral tube, thereby resulting in increases in the manufacturing cost.